Protein kinases, the largest family of human enzymes, encompass well over 500 proteins. Spleen Tyrosine Kinase (SYK) is a member of the family of tyrosine kinases, and is a regulator of early B-cell development as well as mature B-cell activation, signaling, and survival. SYK has roles in immunoreceptor- and integrin-mediated signaling in a variety of cell types, including B-cells, macrophages, monocytes, mast cells, eosinophils, basophils, neutrophils, dendritic cells, T-cells, natural killer cells, platelets, and osteoclasts. The inhibition of Syk activity can be useful for the treatment cancers and inflammatory diseases. U.S. Pat. Nos. 8,455,493, 8,440,667, 9,376,441, 9,416,111, 9,353,066 and 9,376,418 disclose SYK inhibitors. Several SYK inhibitors are in advanced stages of clinical trials. Fostamatinib is a SYK inhibitor currently undergoing phase III clinical trials for chronic immune thrombocytopenic purpura (chronic ITP). (NCT02076412; Clinicaltrials.gov). Fostamatinib, however, has adverse side effects including hypertension, neutropenia and transaminitis. (Nijjar J. S., et al., Rheumatology 2013, 1556-1562).